We can classify different types of "light" or electromagnetic radiation by their wavelengths (or frequency).
We typical use 7 categories ranging from the shortest wavelength to the longest.
In order from shortest to longest wavelength we have:
Gamma Rays
X-Rays
Ultraviolet Radiation
Visible Light
Infrared Radiation
Microwaves
Radio waves
Note: they are all radiation and they are all waves (and they are all "light"), but we typically use different names for different categories.
The Visible Region: It is worth memorizing some of the details of the visible region - it serves as a "marker" region for the other regions. Even though the colors of the visible spectrum fade off into the "invisible" ultra-violet and infra-red regions we generally say that the visible spectrum is located between 400 nm and 700 nm. It is also handy to remember the order of color in the visible region. The easiest (and oldest) is to remember "Roy G. Biv". That will help you remember the order of colors of the visible spectrum (or of the rainbow if you prefer). Don't worry about specific wavelengths other than knowing that 400 nm is the "blue" end of the spectrum and 700 nm is the "red" end. The visible spectrum show below:
The diagram below (from Wikipedia) shows all of the regions within the electromagnetic spectrum. They try to give you a nice real world object to compare the wavelength to. You can (and should) read more at the Wikipedia website: //en.wikipedia.org/wiki/Electromagnetic_spectrum
